Position determining apparatus and associated method

Abstract

The invention relates to a position determining apparatus ( 6 ) for determining the position of an interventional instrument ( 1 ) within a subject ( 4 ). A spatial relation between positions of a second part ( 3 ) of the interventional instrument outside the subject and a first part ( 2 ) of the interventional instrument within the subject is determined based on an actual image of the interventional instrument within the subject being preferentially an x-ray image and a provided position of the second part. Once the spatial relation has been determined, the position of the interventional instrument within the subject can be determined, while the interventional instrument is moved within the subject, based on the determined spatial relation and a determined actual position of the second part outside the subject, without necessarily acquiring a further actual image. This can allow for a reduction of a radiation dose, if rays are used for acquiring the actual image.

The invention claimed is: 
     
       1. A system for determining positions of an interventional instrument within a subject, the system comprising:
 a computer, wherein the computer is configured to run a computer program to: 
 provide an image data set of an interior of the subject as a provided image data set; 
 subsequent to a first part of the interventional instrument being introduced into the subject, determine positions of a second part of the interventional instrument outside of the subject; 
 acquire an x-ray projection image, separate from the provided image data set, of the first part of the interventional instrument introduced within the subject; 
 determine a spatial relation between the positions of the second part and positions of the first part based on (i) the x-ray projection image of the first part introduced within the subject and (ii) the positions of the second part; and 
 determine positions of the first part within the provided image data set, without having to further image the first part, based on images that are only from the provided image data set and the x-ray projection image, and based on the positions of the second part and the spatial relation between the positions of the second part and the positions of the first part, as determined via determining the spatial relation between the positions of the second part and the positions of the first part. 
 
     
     
       2. The system of  claim 1 , wherein the computer program is further run to:
 determine a position of a distal tip of the first part based on the x-ray projection image and determine the spatial relation between the positions of the second part and the positions of the first part by determining a spatial relation between the positions of the second part and the position of the distal tip, and 
 determine the position of the distal tip within the provided image data set depending on (i) the positions of the second part and (ii) the spatial relation between the positions of the second part and the position of the distal tip. 
 
     
     
       3. The system of  claim 2 ,
 wherein the x-ray projection image shows the distal tip of the first part within the subject; and 
 wherein the computer program is further run to determine the position of the distal tip within the subject by detecting the distal tip in the x-ray projection image. 
 
     
     
       4. The system of  claim 2 , wherein the first part is a bendable part having a known length within the subject, and
 wherein the computer program is further run to: 
 detect a shape of the first part within the subject as a detected shape, and determine the position of the distal tip within the subject depending on the detected shape and the known length within the subject. 
 
     
     
       5. The system of  claim 4 , wherein the x-ray projection image shows an intermediate region of the first part within the subject, and
 wherein the computer program is further run to: 
 detect a shape of the first part, thereby detecting a pathway of the intermediate region within the subject as a detected pathway, and determine the position of the distal tip by extrapolating the detected pathway to an end of the known length within the subject. 
 
     
     
       6. The system of  claim 1 , wherein the spatial relation between the positions of the second part and the positions of the first part is determined further based on (i) a shape of the first part within the subject and (ii) the positions of the second part, wherein the shape of the first part within the subject is determined by optical shape sensing with a constraint that the shape of the first part has to correspond to an actual shape of the first part shown in the x-ray projection image. 
     
     
       7. The system of  claim 1 , wherein the computer program is further run to:
 provide at least two x-ray projection images including the x-ray projection image, wherein the at least two x-ray projection images have been acquired in different acquisition directions, and 
 determine the positions of the first part based on the at least two x-ray projection images. 
 
     
     
       8. The system of  claim 1 , wherein the spatial relation between the positions of the second part and the positions of the first part is further determined by correcting another spatial relation that is initially provided based on (i) the first part shown in the x-ray projection image and (ii) the positions of the second part. 
     
     
       9. The system of  claim 1 , wherein the computer program is further run to:
 determining the positions of the second part by at least one of an optical technique and a magnetic technique. 
 
     
     
       10. The system of  claim 1 , further comprising:
 a display that displays a representation of the first part at the positions of the first part within the provided image data set. 
 
     
     
       11. The system of  claim 1 , further comprising:
 the interventional instrument. 
 
     
     
       12. A method for determining positions of an interventional instrument within a subject, the method comprising:
 providing an image data set of an interior of the subject as a provided image data set; 
 subsequent to a first part of the interventional instrument being introduced into the subject, determining positions of a second part of the interventional instrument outside the subject; 
 generating an x-ray projection image, separate from the provided image data set, of the first part of the interventional instrument introduced within the subject; 
 determining a spatial relation between the positions of the second part and positions of the first part based on (i) the x-ray projection image of the first part introduced within the subject and (ii) the positions of the second part; and 
 determining positions of the first part within the provided image data set, without having to further image the first part, based on images that are only from the provided image data set and the x-ray projection image, and based on the positions of the second part and the spatial relation between the positions of the second part and the positions of the first part, as determined via determining the spatial relation between the positions of the second part and the positions of the first part. 
 
     
     
       13. The method of  claim 12 ,
 wherein the method is implemented by a computer program of instructions embodied on a non-transitory computer program element and executable by a computer for determining positions of the interventional instrument within the subject, and in response to the computer program being executed on the computer. 
 
     
     
       14. The method of  claim 12 ,
 wherein the method is implemented by a computer program of instructions embodied on a non-transitory computer readable medium and executable by an interventional system for performing an interventional procedure, and in response to the computer program being executed on the computer. 
 
     
     
       15. A non-transitory computer readable medium containing a program, executable by a computer processor of a computer of a system for performing an interventional procedure on a subject,
 wherein, when executed by the computer processor, the program causes the system for performing an interventional procedure to perform a process comprising: 
 providing an image data set of an interior of the subject as a provided image data set; 
 subsequent to a first part of an interventional instrument being introduced into the subject, determining positions of a second part of an interventional instrument outside the subject; 
 generating an x-ray projection image, separate from the provided image data set, of the first part of the interventional instrument introduced within the subject; 
 determining a spatial relation between the positions of the second part and positions of the first part based on (i) the x-ray projection image of the first part introduced within the subject and (ii) the positions of the second part; and 
 determining positions of the first part within the provided image data set, without having to further image the first part, based on images that are only from the provided image data set and the x-ray projection image, and based on the positions of the second part, and the spatial relation between the positions of the second part and the positions of the first part, as determined in determining the spatial relation between the positions of the second part and the positions of the first part. 
 
     
     
       16. The method of  claim 12 ,
 wherein the image data set of the interior of the subject is generated before acquiring the x-ray projection image. 
 
     
     
       17. The method of  claim 16 ,
 wherein the image data set is generated by a computed tomography system. 
 
     
     
       18. The non-transitory computer readable medium of  claim 15 ,
 wherein the image data set of the interior of the subject is generated before acquiring the x-ray projection image. 
 
     
     
       19. The computer readable medium of  claim 18 ,
 wherein the image data set is generated by a computed tomography system.